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Quantum secret sharing (QSS) enables a dealer to securely distribute keys to multiple players. Device-independent (DI) QSS can resist all possible attacks from practical imperfect devices and provide QSS the highest level of security in theory. However, DI QSS requires high-performance devices, especially for low-noise channels, which is a big challenge for its experimental demonstration. We propose a DI QSS protocol with the advanced random key generation basis strategy, which combines the random key generation basis with the noise preprocessing and postselection strategies. We develop the methods to simplify Eve's conditional entropy bound and numerically simulate the key generation rate in an acceptable time. Our DI QSS protocol has some advantages. First, it can increase the noise tolerance threshold from initial 7.147% to 9.231% (29.16% growth), and reduce the global detection efficiency threshold from 96.32% to 93.41%. The maximal distance between any two users increases to 1.43 km, which is about 5.5 times of the initial value. Second, by randomly selecting two basis combinations to generate the key, our DI QSS protocol can reduce the entanglement resource consumption. Our protocol has potential for DI QSS's experimental demonstration and application in the future., Comment: 16 pages, 6 figures, 1 table

Multi-photon hyperentangement is of fundamental importance in optical quantum information processing. Existing theory and experiment producing multi-photon hyperentangled states have until now relied on the outcome post-selection, a procedure where only the measurement results corresponding to the desired state are considered. Such approach severely limits the usefulness of the resulting hyperentangled states. We present the protocols of direct production of three- and four-photon hyperentanglement and extend the approach to an arbitrary number of photons through a straightforward cascade of spontaneous parametric down-conversion (SPDC) sources. The generated multi-photon hyperentangled states are encoded in polarization-spatial modes and polarization-time bin degrees of freedom, respectively. Numerical calculation shows that if the average photon number $\mu$ is set to 1, the down conversion efficiency is $7.6*10^{-6}$ and the repetition frequency of the laser is $10^9$ Hz, the number of the generation of three-photon and four-photon hyperentanglement after cascading can reach about $5.78*10^{-2}$ and $4.44*10^{-7}$ pairs per second, respectively. By eliminating the constraints of outcome post-selection, our protocols may represent important progresses for multi-photon hyperentangement generation and providing a pivotal role in future multi-party and high-capacity communication networks.

We present CFEVER, a Chinese dataset designed for Fact Extraction and VERification. CFEVER comprises 30,012 manually created claims based on content in Chinese Wikipedia. Each claim in CFEVER is labeled as "Supports", "Refutes", or "Not Enough Info" to depict its degree of factualness. Similar to the FEVER dataset, claims in the "Supports" and "Refutes" categories are also annotated with corresponding evidence sentences sourced from single or multiple pages in Chinese Wikipedia. Our labeled dataset holds a Fleiss' kappa value of 0.7934 for five-way inter-annotator agreement. In addition, through the experiments with the state-of-the-art approaches developed on the FEVER dataset and a simple baseline for CFEVER, we demonstrate that our dataset is a new rigorous benchmark for factual extraction and verification, which can be further used for developing automated systems to alleviate human fact-checking efforts. CFEVER is available at https://ikmlab.github.io/CFEVER., Comment: AAAI-24

Quantum secure direct communications (QSDC) can directly transmit secret messages through a quantum channel without keys. The imperfect photon source is a major obstacle for QSDC's practical implementation. The unwanted vacuum state and multiphoton components emitted from imperfect photon source largely reduce QSDC's secrecy message capacity and even threaten its security. In the paper, we propose a high-efficient passive decoy-state QSDC protocol with the heralded single-photon source (HSPS). We adopt a spontaneous parametric down-conversion source to emit entangled photon pairs in two spatial modes. By detecting the photons in one of the two correlated spatial modes, we can infer the photon-number distribution of the other spatial mode. Meanwhile, our protocol allows a simple passive preparation of the signal states and decoy state. The HSPS can effectively reduce the probability of vacuum state and increase QSDC's secrecy message capacity. Meanwhile, the passive decoy-state method can simplify the experimental operations and enhance QSDC's robustness against the third-party side-channel attacks. Under the communication distance of 10 km, the secrecy message capacity of our QSDC protocol can achieve 81.85 times with average photon number of 0.1 and 12.79 times with average photon number of 0.01 of that in the original single-photon-based QSDC protocol without the HSPS. Our QSDC protocol has longer maximal communication distance about 17.975 km with average photon number of 0.01. Our work serves as a major step toward the further development of practical passive decoy-state QSDC systems., Comment: 13 pages, 5 figures

We study the $\Upsilon$ exclusive decay into double charmonium, specifically, the $S$-wave charmonium $ J/\psi$ plus the $P$-wave charmonium $\chi_{c0,1,2}$ in the NRQCD factorization framework. Three distinct decay mechanisms, i.e., the strong, electromagnetic and radiative decay channels are included and their interference effects are investigated. The decay processes $\Upsilon(1S,2S,3S)\to J/\psi+\chi_{c1,0}$ are predicted to have the branching fractions of order $10^{-6}$, which should be observed in the prospective Super $B$ factory., Comment: 22 pages, 9 figures, 3 tables

In the framework of nonrelativistic QCD, we study the radiative decays of bottomonia into charmonia, including $\Upsilon\to \chi_{cJ}\gamma$, $\Upsilon\to \eta_c\gamma$, $\eta_b\to J/\psi\gamma$, and $\chi_{bJ}\to J/\psi\gamma$. We give predictions for their branching ratios with numerical calculations. E.g., we predict the branching ratio for $\eta_b\to J/\psi\gamma$ is about $1\times 10^{-7}$. As a phenomenological model study, we further extend our calculation to the radiative decays of bottomonia into light mesons by assuming the $f_2(1270)$, $f_2'(1525)$ and other light mesons to be described by nonrelativistic $q\bar q ~(q=u,d,s)$ bound states with constituent quark masses. The calculated branching ratios for $\Upsilon\to f_2(1270)\gamma$ and $\Upsilon\to f_2'(1525)\gamma$ are roughly consistent with the CLEO data. Comparisons with radiative decays of charmonium into light mesons such as $J/\psi\to f_2(1270)\gamma$ are also given. In all calculations the QED contributions are taken into account and found to be significant in some processes.

We apply perturbative QCD to the radiative decays of charmonia $J/\psi$ and $\chi_{cJ}$ into light mesons. We perform a complete numerical calculation for the quark-gluon loop diagrams involved in these processes. The calculated $J/\psi$ decay branching ratios to P-wave mesons $f_2(1270)$ and $f_1(1285)$ fit the data well, while that of $f_0(980)$ (if treated as an $s\bar s$ meson) is predicted to be $1.6\times 10^{-4}$, which implies that $f_0(1710)$ can not be the $s\bar s$ or $(u\bar u+d\bar d)/\sqrt{2}$ meson. Decays of P-wave charmonia $\chi_{cJ}\to \rho(\omega, \phi)\gamma$ (J=0,1,2) are also studied, and the branching ratio of $\chi_{c1}\to \rho\gamma$ is predicted to be $1.4\times 10^{-5}$, which may be tested by CLEO-c and BESIII with future experiments., Comment: journal version; a note on the f_2(1270) helicity added

We study the factorization-forbidden decays $B\to h_c K$ and $B\to\chi_{c2}K$ in the QCD factorization approach. If neglecting the vertex corrections and regularizing the end-point singularities in spectator corrections properly, we get small branching ratios for both the two decay modes, which are roughly consistent with the experimental upper limits. This is in contrast to another factorization-forbidden decay $B\to \chi_{c0}K$, for which a large decay rate is obtained in the same approach., Comment: 5 pages, 1 figure, presentation of the summary is improved

We study radiative decays of $\Upsilon$ to light quark jets in nonrelativistic QCD by taking both the color singlet and color octet $b\bar b$ operators into consideration. The cut for quark jet energy and cut for the angle between two quark jets are introduced. The sensitivity to the soft and collinear singularities in the loop integrals are greatly reduced by these cuts. With the jet energy cut of about 1 GeV, and the jet angle cut of about $36^\circ$, the branching ratio for $\Upsilon\to\gamma q\bar q$ is found to be $8.2\times 10^{-4}$ from color singlet contributions. The color octet contributions could be much larger than that of color singlet, depending on the estimate of the color octet matrix elements. This process may provide a new test for the color octet mechanism in nonrelativistic QCD., Comment: journal version; a few references added

Belle has observed surprisingly copious production of $\psi(3770)$ in $B$ meson decay $B\to \psi(3770)K$, of which the rate is comparable to that of $B\to \psi(3686)K$. We study this puzzling process in the QCD factorization approach with the effect of S-D mixing considered. We find that the soft scattering effects in the spectator interactions play an essential role. With a proper parametrization for the higher twist soft end-point singularities associated with kaon, and with the S-D mixing angle $\theta=-12^{\circ}$, the calculated decay rates can be close to the data. Implications of these soft spectator effects to other charmonium production in $B$ exclusive decays are also emphasized., Comment: journal version

$B\to\chi_{c1}(1P,2P)K$ decays are studied in QCD factorization by treating charmonia as nonrelativistic bound states. No infrared divergences exist in the vertex corrections, while the logarithmic end-point singularities in the hard spectator corrections can be regularized by a momentum cutoff. With certain uncertainties we find that the $B\to\chi_{c1}(2P)K$ decay rate can be comparable to $B\to\chi_{c1}(1P)K$, and get $Br(B^0 \to \chi_{c1}' K^0) =Br(B^+ \to \chi_{c1}' K^+)\approx 2\times 10^{-4}$. This might imply a possible interpretation for the newly discovered X(3872) that this state has a dominant $J^{PC} = 1^{++}(2P)$ $c\bar c$ component but mixed with a substantial $D^0\bar{D}^{*0}+D^{*0}\bar{D}^0$ continuum component., Comment: 5 pages, one figure, new value of decay constant f_B=216 Mev used; references added

We study the unexpectedly large rate for the factorization-forbidden decay $B\to \chi_{c0}K$ within the QCD factorization approach. We use a non-zero gluon mass to regularize the infrared divergences in vertex corrections. The end-point singularities arising from spectator corrections are regularized and carefully estimated by the off-shellness of quarks. We find that the contributions arising from the vertex and leading-twist spectator corrections are numerically small, and the twist-3 spectator contribution with chiral enhancement and linear end-point singularity becomes dominant. With reasonable choices for the parameters, the branching ratio for $B\to\chi_{c0}K$ decay is estimated to be in the range $(2-4)\times 10^{-4}$, which is compatible with the Belle and BaBar data., Comment: Appendix added; it is emphasized that in the dominant twist-3 spectator corrections the end-point singularity contributions may be estimated by the off-shellness of the charm quark (by the binding energy in charmonium) and the gluon (by the transverse momentum of the light quark in the kaon)

In the framework of QCD factorization, we study the $B$ meson exclusive decays $B\to \chi_{cJ}K$ where the spin-triplet P-wave charmonium states $\chi_{cJ}(J=0,1,2)$ are described by the color-singlet non-relativistic wave functions. We find that for these decays (except $\chi_{c1}$) there are infrared divergences arising from nonfactorizable vertex corrections as well as logarithmic end-point singularities arising from nonfactorizable spectator interactions at leading-twist order. The infrared divergences due to vertex corrections will explicitly break down QCD factorization within the color-singlet model for charmonia. Unlike in the inclusive decays where the higher Fock states with color-octet $c \bar c$ pair and soft gluon can make contributions to remove the infrared divergences, their contributions can not be accommodated in the exclusive two body decays. As a result, the infrared divergences encountered in exclusive processes involving charmonia may raise a new question to the QCD factorization and NRQCD factorization in B exclusive decays., Comment: 4 pages, revtex, 1 figure